As a fuel-cell system, one, which has a fuel cell for generating electric power by fuel gas, a condenser for generating condensed water by condensing water content, which is included in the fuel gas to be supplied to the fuel cell, and a reservoir for reserving the condensed water being collected at the condenser, has been known.
When turning off the operation of the aforementioned fuel-cell system, it is turned off completely after cooling a reformer for reforming fuel gas to a certain extent, and is thereafter stood to cool. Moreover, in the fuel-cell system, when the operation is turned off, for the purpose of the inhibition of mingling foreign materials, the protection of catalyst within the reformer, and the like, the vicinities of the reformer and condenser are turned into an enclosed space by shutting off opening-closing valve, and are not opened to atmosphere. Accordingly, when turning off the operation of the fuel-cell system, the aforementioned enclosed space cools gradually from such a state that it has heat. At this moment, water condenses by the fact that gas, which includes water vapor abundantly, is cooled. Therefore, the inside of the enclosed space turns into negative pressure. In this state, if a drain valve, which is connected to the condenser, is opened in order to discharge water that is collected in the condenser, there is a fear that the water, which is collected in the reservoir, might have flowed backward to the condenser side (negative pressure side) by way of the drain valve because of the influence of the negative pressure.
In Patent Literature No. 1, in fuel-cell system, a technique is disclosed, technique that relates to a start-up method of fuel-cell system in which a heat exchanger is disposed on the downstream sides of reformer, CO transformer and CO remover, respectively; and in which exclusive piping is disposed to the respective heat exchangers. According to this one, it is made so that, before getting the start-up started, inert gas is supplied to the respective heat exchangers; and then condensed water, which resides inside the respective heat exchangers, is discharged out of the respective heat exchangers; and thereafter the fuel-cell system is started up. According to this one, since it is possible to discharge the condensed water, which resides inside the respective heat exchangers, by the inactive gas, it is possible to warm up the respective reformer, CO transformer and CO reducer at an early stage.
Moreover, in Patent Literature No. 2, a fuel-cell system is disclosed, fuel-cell system which has a condenser for condensing water content, which is included in fuel gas; two or more gas-liquid separators for letting condensed water undergo gas-liquid separation; a collected-water reservoir for reserving condensed water, which is subjected to gas-liquid separation at the respective gas-liquid separators; drain passages, which connect between the gas-liquid separators and the collected-water reservoir; and a valve mechanism being disposed in the drain passages. According to this one, a controller controls the valve mechanisms so that the multiple gas-liquid separators do not pass water to each other by way of the drain passages. Thus, it is made so as to prevent the backward flow of water, which results from differential pressures arising mutually between the multiple gas-liquid separators.
Moreover, in Patent Literature No. 3, a fuel-reforming apparatus is disclosed, fuel-reforming apparatus in which are former for reforming fuel gas into hydrogen-rich gas, and a CO reducer for reducing CO, which is included in gas after reforming, are disposed; and further in which a drain hole is formed in the bottom of the reformer, and a drain hole is formed in the bottom of the CO reducer. According to this one, a fuel-reforming apparatus for fuel cell is disclosed, fuel-reforming apparatus that discharges: liquid content, which is collected in the reformer; and liquid content, which is collected in the CO reducer; when starting up the system.
[Patent Literature No. 1] Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2002-260, 699;
[Patent Literature No. 2] Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2004-220, 876; and
[Patent Literature No. 3] Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2004-182, 531